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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Written by Doug Lea and Martin Buchholz with assistance from<a name="line.2"></a>
<span class="sourceLineNo">003</span> * members of JCP JSR-166 Expert Group and released to the public<a name="line.3"></a>
<span class="sourceLineNo">004</span> * domain, as explained at<a name="line.4"></a>
<span class="sourceLineNo">005</span> * http://creativecommons.org/publicdomain/zero/1.0/<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>/*<a name="line.8"></a>
<span class="sourceLineNo">009</span> * Source:<a name="line.9"></a>
<span class="sourceLineNo">010</span> * http://gee.cs.oswego.edu/cgi-bin/viewcvs.cgi/jsr166/src/jsr166e/extra/AtomicDouble.java?revision=1.13<a name="line.10"></a>
<span class="sourceLineNo">011</span> * (Modified to adapt to guava coding conventions and<a name="line.11"></a>
<span class="sourceLineNo">012</span> * to use AtomicLongFieldUpdater instead of sun.misc.Unsafe)<a name="line.12"></a>
<span class="sourceLineNo">013</span> */<a name="line.13"></a>
<span class="sourceLineNo">014</span><a name="line.14"></a>
<span class="sourceLineNo">015</span>package com.google.common.util.concurrent;<a name="line.15"></a>
<span class="sourceLineNo">016</span><a name="line.16"></a>
<span class="sourceLineNo">017</span>import static java.lang.Double.doubleToRawLongBits;<a name="line.17"></a>
<span class="sourceLineNo">018</span>import static java.lang.Double.longBitsToDouble;<a name="line.18"></a>
<span class="sourceLineNo">019</span><a name="line.19"></a>
<span class="sourceLineNo">020</span>import com.google.common.annotations.Beta;<a name="line.20"></a>
<span class="sourceLineNo">021</span><a name="line.21"></a>
<span class="sourceLineNo">022</span>import java.util.concurrent.atomic.AtomicLongFieldUpdater;<a name="line.22"></a>
<span class="sourceLineNo">023</span><a name="line.23"></a>
<span class="sourceLineNo">024</span>/**<a name="line.24"></a>
<span class="sourceLineNo">025</span> * A {@code double} value that may be updated atomically.  See the<a name="line.25"></a>
<span class="sourceLineNo">026</span> * {@link java.util.concurrent.atomic} package specification for<a name="line.26"></a>
<span class="sourceLineNo">027</span> * description of the properties of atomic variables.  An {@code<a name="line.27"></a>
<span class="sourceLineNo">028</span> * AtomicDouble} is used in applications such as atomic accumulation,<a name="line.28"></a>
<span class="sourceLineNo">029</span> * and cannot be used as a replacement for a {@link Double}.  However,<a name="line.29"></a>
<span class="sourceLineNo">030</span> * this class does extend {@code Number} to allow uniform access by<a name="line.30"></a>
<span class="sourceLineNo">031</span> * tools and utilities that deal with numerically-based classes.<a name="line.31"></a>
<span class="sourceLineNo">032</span> *<a name="line.32"></a>
<span class="sourceLineNo">033</span> * &lt;p&gt;&lt;a name="bitEquals"&gt;This class compares primitive {@code double}<a name="line.33"></a>
<span class="sourceLineNo">034</span> * values in methods such as {@link #compareAndSet} by comparing their<a name="line.34"></a>
<span class="sourceLineNo">035</span> * bitwise representation using {@link Double#doubleToRawLongBits},<a name="line.35"></a>
<span class="sourceLineNo">036</span> * which differs from both the primitive double {@code ==} operator<a name="line.36"></a>
<span class="sourceLineNo">037</span> * and from {@link Double#equals}, as if implemented by:<a name="line.37"></a>
<span class="sourceLineNo">038</span> *  &lt;pre&gt; {@code<a name="line.38"></a>
<span class="sourceLineNo">039</span> * static boolean bitEquals(double x, double y) {<a name="line.39"></a>
<span class="sourceLineNo">040</span> *   long xBits = Double.doubleToRawLongBits(x);<a name="line.40"></a>
<span class="sourceLineNo">041</span> *   long yBits = Double.doubleToRawLongBits(y);<a name="line.41"></a>
<span class="sourceLineNo">042</span> *   return xBits == yBits;<a name="line.42"></a>
<span class="sourceLineNo">043</span> * }}&lt;/pre&gt;<a name="line.43"></a>
<span class="sourceLineNo">044</span> *<a name="line.44"></a>
<span class="sourceLineNo">045</span> * &lt;p&gt;It is possible to write a more scalable updater, at the cost of<a name="line.45"></a>
<span class="sourceLineNo">046</span> * giving up strict atomicity.  See for example<a name="line.46"></a>
<span class="sourceLineNo">047</span> * &lt;a href="http://gee.cs.oswego.edu/dl/jsr166/dist/jsr166edocs/jsr166e/DoubleAdder.html"<a name="line.47"></a>
<span class="sourceLineNo">048</span> * DoubleAdder&gt;<a name="line.48"></a>
<span class="sourceLineNo">049</span> * and<a name="line.49"></a>
<span class="sourceLineNo">050</span> * &lt;a href="http://gee.cs.oswego.edu/dl/jsr166/dist/jsr166edocs/jsr166e/DoubleMaxUpdater.html"<a name="line.50"></a>
<span class="sourceLineNo">051</span> * DoubleMaxUpdater&gt;.<a name="line.51"></a>
<span class="sourceLineNo">052</span> *<a name="line.52"></a>
<span class="sourceLineNo">053</span> * @author Doug Lea<a name="line.53"></a>
<span class="sourceLineNo">054</span> * @author Martin Buchholz<a name="line.54"></a>
<span class="sourceLineNo">055</span> * @since 11.0<a name="line.55"></a>
<span class="sourceLineNo">056</span> */<a name="line.56"></a>
<span class="sourceLineNo">057</span>@Beta<a name="line.57"></a>
<span class="sourceLineNo">058</span>public class AtomicDouble extends Number implements java.io.Serializable {<a name="line.58"></a>
<span class="sourceLineNo">059</span>  private static final long serialVersionUID = 0L;<a name="line.59"></a>
<span class="sourceLineNo">060</span><a name="line.60"></a>
<span class="sourceLineNo">061</span>  private transient volatile long value;<a name="line.61"></a>
<span class="sourceLineNo">062</span><a name="line.62"></a>
<span class="sourceLineNo">063</span>  private static final AtomicLongFieldUpdater&lt;AtomicDouble&gt; updater =<a name="line.63"></a>
<span class="sourceLineNo">064</span>      AtomicLongFieldUpdater.newUpdater(AtomicDouble.class, "value");<a name="line.64"></a>
<span class="sourceLineNo">065</span><a name="line.65"></a>
<span class="sourceLineNo">066</span>  /**<a name="line.66"></a>
<span class="sourceLineNo">067</span>   * Creates a new {@code AtomicDouble} with the given initial value.<a name="line.67"></a>
<span class="sourceLineNo">068</span>   *<a name="line.68"></a>
<span class="sourceLineNo">069</span>   * @param initialValue the initial value<a name="line.69"></a>
<span class="sourceLineNo">070</span>   */<a name="line.70"></a>
<span class="sourceLineNo">071</span>  public AtomicDouble(double initialValue) {<a name="line.71"></a>
<span class="sourceLineNo">072</span>    value = doubleToRawLongBits(initialValue);<a name="line.72"></a>
<span class="sourceLineNo">073</span>  }<a name="line.73"></a>
<span class="sourceLineNo">074</span><a name="line.74"></a>
<span class="sourceLineNo">075</span>  /**<a name="line.75"></a>
<span class="sourceLineNo">076</span>   * Creates a new {@code AtomicDouble} with initial value {@code 0.0}.<a name="line.76"></a>
<span class="sourceLineNo">077</span>   */<a name="line.77"></a>
<span class="sourceLineNo">078</span>  public AtomicDouble() {<a name="line.78"></a>
<span class="sourceLineNo">079</span>    // assert doubleToRawLongBits(0.0) == 0L;<a name="line.79"></a>
<span class="sourceLineNo">080</span>  }<a name="line.80"></a>
<span class="sourceLineNo">081</span><a name="line.81"></a>
<span class="sourceLineNo">082</span>  /**<a name="line.82"></a>
<span class="sourceLineNo">083</span>   * Gets the current value.<a name="line.83"></a>
<span class="sourceLineNo">084</span>   *<a name="line.84"></a>
<span class="sourceLineNo">085</span>   * @return the current value<a name="line.85"></a>
<span class="sourceLineNo">086</span>   */<a name="line.86"></a>
<span class="sourceLineNo">087</span>  public final double get() {<a name="line.87"></a>
<span class="sourceLineNo">088</span>    return longBitsToDouble(value);<a name="line.88"></a>
<span class="sourceLineNo">089</span>  }<a name="line.89"></a>
<span class="sourceLineNo">090</span><a name="line.90"></a>
<span class="sourceLineNo">091</span>  /**<a name="line.91"></a>
<span class="sourceLineNo">092</span>   * Sets to the given value.<a name="line.92"></a>
<span class="sourceLineNo">093</span>   *<a name="line.93"></a>
<span class="sourceLineNo">094</span>   * @param newValue the new value<a name="line.94"></a>
<span class="sourceLineNo">095</span>   */<a name="line.95"></a>
<span class="sourceLineNo">096</span>  public final void set(double newValue) {<a name="line.96"></a>
<span class="sourceLineNo">097</span>    long next = doubleToRawLongBits(newValue);<a name="line.97"></a>
<span class="sourceLineNo">098</span>    value = next;<a name="line.98"></a>
<span class="sourceLineNo">099</span>  }<a name="line.99"></a>
<span class="sourceLineNo">100</span><a name="line.100"></a>
<span class="sourceLineNo">101</span>  /**<a name="line.101"></a>
<span class="sourceLineNo">102</span>   * Eventually sets to the given value.<a name="line.102"></a>
<span class="sourceLineNo">103</span>   *<a name="line.103"></a>
<span class="sourceLineNo">104</span>   * @param newValue the new value<a name="line.104"></a>
<span class="sourceLineNo">105</span>   */<a name="line.105"></a>
<span class="sourceLineNo">106</span>  public final void lazySet(double newValue) {<a name="line.106"></a>
<span class="sourceLineNo">107</span>    set(newValue);<a name="line.107"></a>
<span class="sourceLineNo">108</span>    // TODO(user): replace with code below when jdk5 support is dropped.<a name="line.108"></a>
<span class="sourceLineNo">109</span>    // long next = doubleToRawLongBits(newValue);<a name="line.109"></a>
<span class="sourceLineNo">110</span>    // updater.lazySet(this, next);<a name="line.110"></a>
<span class="sourceLineNo">111</span>  }<a name="line.111"></a>
<span class="sourceLineNo">112</span><a name="line.112"></a>
<span class="sourceLineNo">113</span>  /**<a name="line.113"></a>
<span class="sourceLineNo">114</span>   * Atomically sets to the given value and returns the old value.<a name="line.114"></a>
<span class="sourceLineNo">115</span>   *<a name="line.115"></a>
<span class="sourceLineNo">116</span>   * @param newValue the new value<a name="line.116"></a>
<span class="sourceLineNo">117</span>   * @return the previous value<a name="line.117"></a>
<span class="sourceLineNo">118</span>   */<a name="line.118"></a>
<span class="sourceLineNo">119</span>  public final double getAndSet(double newValue) {<a name="line.119"></a>
<span class="sourceLineNo">120</span>    long next = doubleToRawLongBits(newValue);<a name="line.120"></a>
<span class="sourceLineNo">121</span>    return longBitsToDouble(updater.getAndSet(this, next));<a name="line.121"></a>
<span class="sourceLineNo">122</span>  }<a name="line.122"></a>
<span class="sourceLineNo">123</span><a name="line.123"></a>
<span class="sourceLineNo">124</span>  /**<a name="line.124"></a>
<span class="sourceLineNo">125</span>   * Atomically sets the value to the given updated value<a name="line.125"></a>
<span class="sourceLineNo">126</span>   * if the current value is &lt;a href="#bitEquals"&gt;bitwise equal&lt;/a&gt;<a name="line.126"></a>
<span class="sourceLineNo">127</span>   * to the expected value.<a name="line.127"></a>
<span class="sourceLineNo">128</span>   *<a name="line.128"></a>
<span class="sourceLineNo">129</span>   * @param expect the expected value<a name="line.129"></a>
<span class="sourceLineNo">130</span>   * @param update the new value<a name="line.130"></a>
<span class="sourceLineNo">131</span>   * @return {@code true} if successful. False return indicates that<a name="line.131"></a>
<span class="sourceLineNo">132</span>   * the actual value was not bitwise equal to the expected value.<a name="line.132"></a>
<span class="sourceLineNo">133</span>   */<a name="line.133"></a>
<span class="sourceLineNo">134</span>  public final boolean compareAndSet(double expect, double update) {<a name="line.134"></a>
<span class="sourceLineNo">135</span>    return updater.compareAndSet(this,<a name="line.135"></a>
<span class="sourceLineNo">136</span>                                 doubleToRawLongBits(expect),<a name="line.136"></a>
<span class="sourceLineNo">137</span>                                 doubleToRawLongBits(update));<a name="line.137"></a>
<span class="sourceLineNo">138</span>  }<a name="line.138"></a>
<span class="sourceLineNo">139</span><a name="line.139"></a>
<span class="sourceLineNo">140</span>  /**<a name="line.140"></a>
<span class="sourceLineNo">141</span>   * Atomically sets the value to the given updated value<a name="line.141"></a>
<span class="sourceLineNo">142</span>   * if the current value is &lt;a href="#bitEquals"&gt;bitwise equal&lt;/a&gt;<a name="line.142"></a>
<span class="sourceLineNo">143</span>   * to the expected value.<a name="line.143"></a>
<span class="sourceLineNo">144</span>   *<a name="line.144"></a>
<span class="sourceLineNo">145</span>   * &lt;p&gt;May &lt;a<a name="line.145"></a>
<span class="sourceLineNo">146</span>   * href="http://download.oracle.com/javase/7/docs/api/java/util/concurrent/atomic/package-summary.html#Spurious"&gt;<a name="line.146"></a>
<span class="sourceLineNo">147</span>   * fail spuriously&lt;/a&gt;<a name="line.147"></a>
<span class="sourceLineNo">148</span>   * and does not provide ordering guarantees, so is only rarely an<a name="line.148"></a>
<span class="sourceLineNo">149</span>   * appropriate alternative to {@code compareAndSet}.<a name="line.149"></a>
<span class="sourceLineNo">150</span>   *<a name="line.150"></a>
<span class="sourceLineNo">151</span>   * @param expect the expected value<a name="line.151"></a>
<span class="sourceLineNo">152</span>   * @param update the new value<a name="line.152"></a>
<span class="sourceLineNo">153</span>   * @return {@code true} if successful<a name="line.153"></a>
<span class="sourceLineNo">154</span>   */<a name="line.154"></a>
<span class="sourceLineNo">155</span>  public final boolean weakCompareAndSet(double expect, double update) {<a name="line.155"></a>
<span class="sourceLineNo">156</span>    return updater.weakCompareAndSet(this,<a name="line.156"></a>
<span class="sourceLineNo">157</span>                                     doubleToRawLongBits(expect),<a name="line.157"></a>
<span class="sourceLineNo">158</span>                                     doubleToRawLongBits(update));<a name="line.158"></a>
<span class="sourceLineNo">159</span>  }<a name="line.159"></a>
<span class="sourceLineNo">160</span><a name="line.160"></a>
<span class="sourceLineNo">161</span>  /**<a name="line.161"></a>
<span class="sourceLineNo">162</span>   * Atomically adds the given value to the current value.<a name="line.162"></a>
<span class="sourceLineNo">163</span>   *<a name="line.163"></a>
<span class="sourceLineNo">164</span>   * @param delta the value to add<a name="line.164"></a>
<span class="sourceLineNo">165</span>   * @return the previous value<a name="line.165"></a>
<span class="sourceLineNo">166</span>   */<a name="line.166"></a>
<span class="sourceLineNo">167</span>  public final double getAndAdd(double delta) {<a name="line.167"></a>
<span class="sourceLineNo">168</span>    while (true) {<a name="line.168"></a>
<span class="sourceLineNo">169</span>      long current = value;<a name="line.169"></a>
<span class="sourceLineNo">170</span>      double currentVal = longBitsToDouble(current);<a name="line.170"></a>
<span class="sourceLineNo">171</span>      double nextVal = currentVal + delta;<a name="line.171"></a>
<span class="sourceLineNo">172</span>      long next = doubleToRawLongBits(nextVal);<a name="line.172"></a>
<span class="sourceLineNo">173</span>      if (updater.compareAndSet(this, current, next)) {<a name="line.173"></a>
<span class="sourceLineNo">174</span>        return currentVal;<a name="line.174"></a>
<span class="sourceLineNo">175</span>      }<a name="line.175"></a>
<span class="sourceLineNo">176</span>    }<a name="line.176"></a>
<span class="sourceLineNo">177</span>  }<a name="line.177"></a>
<span class="sourceLineNo">178</span><a name="line.178"></a>
<span class="sourceLineNo">179</span>  /**<a name="line.179"></a>
<span class="sourceLineNo">180</span>   * Atomically adds the given value to the current value.<a name="line.180"></a>
<span class="sourceLineNo">181</span>   *<a name="line.181"></a>
<span class="sourceLineNo">182</span>   * @param delta the value to add<a name="line.182"></a>
<span class="sourceLineNo">183</span>   * @return the updated value<a name="line.183"></a>
<span class="sourceLineNo">184</span>   */<a name="line.184"></a>
<span class="sourceLineNo">185</span>  public final double addAndGet(double delta) {<a name="line.185"></a>
<span class="sourceLineNo">186</span>    while (true) {<a name="line.186"></a>
<span class="sourceLineNo">187</span>      long current = value;<a name="line.187"></a>
<span class="sourceLineNo">188</span>      double currentVal = longBitsToDouble(current);<a name="line.188"></a>
<span class="sourceLineNo">189</span>      double nextVal = currentVal + delta;<a name="line.189"></a>
<span class="sourceLineNo">190</span>      long next = doubleToRawLongBits(nextVal);<a name="line.190"></a>
<span class="sourceLineNo">191</span>      if (updater.compareAndSet(this, current, next)) {<a name="line.191"></a>
<span class="sourceLineNo">192</span>        return nextVal;<a name="line.192"></a>
<span class="sourceLineNo">193</span>      }<a name="line.193"></a>
<span class="sourceLineNo">194</span>    }<a name="line.194"></a>
<span class="sourceLineNo">195</span>  }<a name="line.195"></a>
<span class="sourceLineNo">196</span><a name="line.196"></a>
<span class="sourceLineNo">197</span>  /**<a name="line.197"></a>
<span class="sourceLineNo">198</span>   * Returns the String representation of the current value.<a name="line.198"></a>
<span class="sourceLineNo">199</span>   * @return the String representation of the current value<a name="line.199"></a>
<span class="sourceLineNo">200</span>   */<a name="line.200"></a>
<span class="sourceLineNo">201</span>  public String toString() {<a name="line.201"></a>
<span class="sourceLineNo">202</span>    return Double.toString(get());<a name="line.202"></a>
<span class="sourceLineNo">203</span>  }<a name="line.203"></a>
<span class="sourceLineNo">204</span><a name="line.204"></a>
<span class="sourceLineNo">205</span>  /**<a name="line.205"></a>
<span class="sourceLineNo">206</span>   * Returns the value of this {@code AtomicDouble} as an {@code int}<a name="line.206"></a>
<span class="sourceLineNo">207</span>   * after a narrowing primitive conversion.<a name="line.207"></a>
<span class="sourceLineNo">208</span>   */<a name="line.208"></a>
<span class="sourceLineNo">209</span>  public int intValue() {<a name="line.209"></a>
<span class="sourceLineNo">210</span>    return (int) get();<a name="line.210"></a>
<span class="sourceLineNo">211</span>  }<a name="line.211"></a>
<span class="sourceLineNo">212</span><a name="line.212"></a>
<span class="sourceLineNo">213</span>  /**<a name="line.213"></a>
<span class="sourceLineNo">214</span>   * Returns the value of this {@code AtomicDouble} as a {@code long}<a name="line.214"></a>
<span class="sourceLineNo">215</span>   * after a narrowing primitive conversion.<a name="line.215"></a>
<span class="sourceLineNo">216</span>   */<a name="line.216"></a>
<span class="sourceLineNo">217</span>  public long longValue() {<a name="line.217"></a>
<span class="sourceLineNo">218</span>    return (long) get();<a name="line.218"></a>
<span class="sourceLineNo">219</span>  }<a name="line.219"></a>
<span class="sourceLineNo">220</span><a name="line.220"></a>
<span class="sourceLineNo">221</span>  /**<a name="line.221"></a>
<span class="sourceLineNo">222</span>   * Returns the value of this {@code AtomicDouble} as a {@code float}<a name="line.222"></a>
<span class="sourceLineNo">223</span>   * after a narrowing primitive conversion.<a name="line.223"></a>
<span class="sourceLineNo">224</span>   */<a name="line.224"></a>
<span class="sourceLineNo">225</span>  public float floatValue() {<a name="line.225"></a>
<span class="sourceLineNo">226</span>    return (float) get();<a name="line.226"></a>
<span class="sourceLineNo">227</span>  }<a name="line.227"></a>
<span class="sourceLineNo">228</span><a name="line.228"></a>
<span class="sourceLineNo">229</span>  /**<a name="line.229"></a>
<span class="sourceLineNo">230</span>   * Returns the value of this {@code AtomicDouble} as a {@code double}.<a name="line.230"></a>
<span class="sourceLineNo">231</span>   */<a name="line.231"></a>
<span class="sourceLineNo">232</span>  public double doubleValue() {<a name="line.232"></a>
<span class="sourceLineNo">233</span>    return get();<a name="line.233"></a>
<span class="sourceLineNo">234</span>  }<a name="line.234"></a>
<span class="sourceLineNo">235</span><a name="line.235"></a>
<span class="sourceLineNo">236</span>  /**<a name="line.236"></a>
<span class="sourceLineNo">237</span>   * Saves the state to a stream (that is, serializes it).<a name="line.237"></a>
<span class="sourceLineNo">238</span>   *<a name="line.238"></a>
<span class="sourceLineNo">239</span>   * @serialData The current value is emitted (a {@code double}).<a name="line.239"></a>
<span class="sourceLineNo">240</span>   */<a name="line.240"></a>
<span class="sourceLineNo">241</span>  private void writeObject(java.io.ObjectOutputStream s)<a name="line.241"></a>
<span class="sourceLineNo">242</span>      throws java.io.IOException {<a name="line.242"></a>
<span class="sourceLineNo">243</span>    s.defaultWriteObject();<a name="line.243"></a>
<span class="sourceLineNo">244</span><a name="line.244"></a>
<span class="sourceLineNo">245</span>    s.writeDouble(get());<a name="line.245"></a>
<span class="sourceLineNo">246</span>  }<a name="line.246"></a>
<span class="sourceLineNo">247</span><a name="line.247"></a>
<span class="sourceLineNo">248</span>  /**<a name="line.248"></a>
<span class="sourceLineNo">249</span>   * Reconstitutes the instance from a stream (that is, deserializes it).<a name="line.249"></a>
<span class="sourceLineNo">250</span>   */<a name="line.250"></a>
<span class="sourceLineNo">251</span>  private void readObject(java.io.ObjectInputStream s)<a name="line.251"></a>
<span class="sourceLineNo">252</span>      throws java.io.IOException, ClassNotFoundException {<a name="line.252"></a>
<span class="sourceLineNo">253</span>    s.defaultReadObject();<a name="line.253"></a>
<span class="sourceLineNo">254</span><a name="line.254"></a>
<span class="sourceLineNo">255</span>    set(s.readDouble());<a name="line.255"></a>
<span class="sourceLineNo">256</span>  }<a name="line.256"></a>
<span class="sourceLineNo">257</span>}<a name="line.257"></a>




























































</pre>
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